Current Physical Chemistry - Volume 8, Issue 4, 2018

Background: Over the last four decades, tremendous growth has been witnessed in the field of electrically conducting polymers. A great deal of theoretical and empirical efforts have been made to achieve multifunctional conducting polymeric structures. However, the major challenge in this field is achieving the minimum band gap value which governs various electronic and optoelectronic properties of the structure. Objective: Artificial optimization viz., metaheuristic algorithms have been clubbed with the polymer problem to investigate the electronic properties of copolymers. Method: Band structures of different homopolymers obtained from ab-initio Hartree-Fock crystal orbital method have been used as input to obtain the electronic properties of copolymers using genetic algorithm, ant colony optimization and particle swarm optimization. Result: Nature-based computing methods employed for tailoring intrinsically conducting copolymers correspond to optimal electronic properties. Conclusion: This computational cloning approach provides a cost-effective and potent passage for taking forward optimized theoretical solutions to synthetic environment.

Background: A perusal of literature survey reveals that a number of transition metal soaps and their complexes have been studied however scanty references are available as to the investigation of copper (II) soap-complexes. The present study also gives an account of our understanding of several aspects of micelle formation of copper soapcomplexes in the mixed non-aqueous solvents. Attempts have also been made to study the physico-chemical properties of Cu(II) soap-complexes in methanol + benzene solvent mixtures and the findings has been reported in this paper. Objective: Owing to proven industrial utility of copper (II) soap complexes, the paper provide a fundamental and informative account of micellar features of three complexes in 40% methanol-benzene and 80% methanol-benzene solvent mixture. The complexes synthesized are abbreviated as follows: (1) Copper-caprylate with 2-amino-6-methyl benzothiazole: CCplAMB (2) Copper-caprate with 2-amino-6-methyl benzothiazole: CCprAMB (3) Copper-laurate with 2-amino-6-methyl benzothiazole: CLrtAMB Method: The density, molar volume, and apparent molar volume of Cu (II) surfactants with substituted 2-amino-6-methyl benzothiazole in 80 % and 40% benzene-methanol mixture has been determined at constant temperature 298.15 K. Results: The results were used to determine the Critical Micelle Concentration (CMC), the effect of chain length of the complex molecule on CMC and complex-solvent interactions. The CMC decreases with the increase in the chain length of fatty acid segment of complex. The apparent molar volume has been examined in terms of Masson equation, and the limiting apparent molar volume has been interpreted in terms of solute-solvent interaction. The solute – solute interactions were found to be greater before CMC whereas solute solvent interactions were found greater after CMC. There is appreciable increase in aggregation of surfactant molecules at a definite concentration and the structure of the aggregates is entirely different below and above CMC. The effect of polarity of the solvent has also been studied. Conclusion: The current topic will contribute to understand the solution behavior, micellar characters and different interactions which exist between solute-solute and solute-solvent molecules for their applications in various fields.

Background: The study of the effect of External Electric Field (EEF) on the structure of several biologically important compounds is now extended to pyrimidine and purine bases. Objectives: The present study involves computations of changes in energy and dipole moments, the charge density of pyrimidine bases (cytosine, thymine and uracil) and purine bases (adenosine and guanine) in the external electric field of 0.00, 5.14, 25.70 and 51.40 MV/cm. Method: The computations were performed applying HyperChem 8.0 software together with the PM3 method for optimization of the conformation of the molecules. Results: The rise in the EEF strength to 5.14 MV/cm has a subtle effect on the molecular energy of the bases under consideration. A slight tendency in decreasing that energy can, however, be observed. On elevating the strength up to 25.70 MV/cm the decrease in molecular energy was more significant. EEF has a tremendous effect on the reorientation of the molecules in the Cartesian system. It influences tautomeric equilibria. Conclusion: Observed changes evoked by the EEF were specific for particular molecules. They resulted mainly from the polarization of the bonds and from steric deformations of the molecules.

Background: Although carbofuran is widely used in agriculture, it is not all decomposed and remains in crops. And then its toxicity is harmful to humans and animals. Objective: The objective of this paper was to consider the effect of various parameters in the preparation process of the Surface Molecularly Imprinting Polymer (SMIP) for the removal of carbofuran and the adsorption study. Method: SMIP was prepared by copolymerizing methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) on the surface of silica gel particles in the presence of the carbofuran template molecules. All adsorption experiment were carried out for 5hours under given conditions. Results: The results show that toluene is suitable as a pretreatment (mixing) solvent for the preparation of SMIP and the pretreatment between the template molecule and the functional monomer was completed in 60 minutes. And the adsorption capacity of SMIP increase with the increasing initial concentration of carbofuran solution and adsorption equilibrium time is less than 50 min. adsorption. The adsorption amount is 8.61 mg/g in adsorption solvent which the ratio of n-hexane to chloroform is 6:1, Maximum adsorption was observed at a pH range of 5-7.The isotherms were well described by the Freundlich equilibrium model, and kinetics were well fitted by the pseudo-second-order kinetic model. Conclusion: In this study, the SMIP was successfully prepared by coating the carbofuran imprinted polymer on the surface of silica gel particles. The results of adsorption experiments show that the prepared SMIP has good selectivity and adsorption capacity, and can effectively remove carbofuran in aqueous solution.

Background: Thermal decomposition of iron-bearing organic complexes is a useful way to prepare iron oxides. Iron(III)citrate, FeC6H5O7, is a precursor for hematite (α-Fe2O3) synthesis by thermal decomposition technique. However, there is no information available on the nature of the mechanism of the reaction. Objective: Kinetic analysis of the solid-state thermal reaction of Iron(III)citrate, which decomposes to hematite under oxidative reaction atmosphere, has been studied in order to understand the reaction process. Method: Non-isothermal thermogravimetry under multiple heating rates has been employed. The obtained data are analyzed using model-free iso-conversional kinetic techniques in order to estimate the activation energy of reaction and reaction rate. Master plot method has been employed to determine the most-probable reaction mechanism. Reaction rate has been used to estimate the thermodynamic parameters (ΔS*, ΔH* and ΔG*). Decomposed material has been studied by XRD and TEM. Observations: Thermal decomposition of Iron(III)citrate is a three-step process and is completed by ~600 K. The decomposed product obtained is hematite nanomaterial. The estimated activation energy and reaction rate values are strongly dependent on the extent of conversion. The initial two steps of thermal decomposition reaction may involve ‘threedimensional diffusion’ and ‘random nucleation’, whereas the third step may be assigned again to ‘three-dimensional diffusion’. Simulated conversion curves justify the estimated kinetic parameters. A reaction pathway has also been predicted.

Background: A kinetic spectrophotometric method based on Ir (III) catalyzed the oxidation of leucine by hexacyanoferrate (III) in the aqueous alkaline medium has been developed for 0.99 μgcm-3 to 19.98 μgcm-3 determination of Ir(III). Method: Molar absorptivity (1.0503 to 1.5003 Lmol-1cm-1), Sandell’s sensitivity (0.183 to 0.128 μgcm-3), correlation coefficient (-0.9872 to 0.9957) and effect of selected interferences have been worked out for developing the calibration curves in terms of absorbance or initial rate or pseudo-first-order rate constant vs. Ir(III) plot. Conclusion: The method is simpler, more sensitive with improved detection limits in comparison to other reported methods and is useful in absence of expected interferants.